1. Field of the Invention
The present invention relates to a ball joint used at an oscillating portion of a suspension of an automobile, and particularly to an improvement in a ball joint comprising a ball stud, a ball socket for swingably retaining a ball-shaped head of the ball stud with a bearing interposed therebetween, a retaining ring having a cylindrical portion press-fitted to an outer peripheral surface of a shank and a pair of large and small flanges protruding from axially outer and inner ends of the cylindrical portion, and a boot having first and second annular beads fitted to the retaining ring and the ball socket, respectively, the first mounting bead being formed with an inner periphery seal portion and an end face seal portion which are adapted to come into close contact with the cylindrical portion and the large flange, respectively.
2. Description of the Related Art
Such a ball joint is already known, for example, as disclosed in Japanese Patent Application Laid-open No. 11-63245.
To form the retaining ring in such a conventional ball joint, the first mounting bead of the boot is first fitted to the cylindrical portion of the retaining ring whose small flange is not yet formed, i.e., the retaining ring having only the large flange formed at one end of the cylindrical portion; and the small flange is then formed by expanding a particular cylindrical portion set at a tip end of the cylindrical portion of the retaining ring from the side of the second mounting bead by an expanding jig for forming the small flange. Thereafter, the shank of the ball stud is press-fitted to the cylindrical portion of the retaining ring.
However, the formation of the small flange of the retaining ring by the special expanding jig after fitting the first mounting bead of the boot to the cylindrical portion of the retaining ring as in the conventional ball joint, results in an increase in the number of steps of assembling the ball joint, which is an obstacle to a reduction in cost.